A typical data storage system includes a magnetic medium for storing data in magnetic form and a transducer used to write and read magnetic data respectively to and from the medium. A disk storage device, for example, includes one or more data storage disks coaxially mounted on a hub of a spindle motor. The spindle motor rotates the disks at speeds typically on the order of several thousand revolutions-per-minute. Digital information is typically stored in the form of magnetic transitions on a series of concentric, spaced tracks comprising the surface of the magnetizable rigid data storage disks. The tracks are generally divided into a plurality of sectors, with each sector comprising a number of information fields, including fields for storing data, and sector identification and synchronization information, for example.
The actuator assembly typically includes a plurality of outwardly extending arms with one or more transducers and slider bodies being mounted on flexible suspensions. A slider body is typically designed as an aerodynamic lifting body that lifts the transducer head off of the surface of the disk as the rate of spindle motor rotation increases, and causes the head to hover above the disk on an air-bearing produced by high speed disk rotation. The distance between the head and the disk surface, typically on the order of 50-100 nanometers (nm) is commonly referred to as head-to-disk spacing.
Writing data to a data storage disk generally involves passing a current through the write element of the transducer assembly to produce magnetic lines of flux which magnetize a specific location of the disk surface. Reading data from a specified disk location is typically accomplished by a read element of the transducer assembly sensing the magnetic field or flux lines emanating from the magnetized locations of the disk. As the read element passes over the rotating disk surface, the interaction between the read element and the magnetized locations on the disk surface results in the production of electrical signals, commonly referred to as readback signals, in the read element.
Conventional data storage systems generally employ a closed-loop servo control system for positioning the read/write transducers to specified storage locations on the data storage disk. During normal data storage system operation, a servo transducer, generally mounted proximate the read/write transducers, or, alternatively, incorporated as the read element of the transducer, is typically employed to read information for the purpose of following a specified track (track following) and locating (seeking) specified track and data sector locations on the disk.
In accordance with one known servo technique, embedded servo pattern information is written to the disk along segments extending in a direction generally outward from the center of the disk. The embedded servo patterns are thus formed between the data storing sectors of each track. It is noted that a servo sector typically contains a pattern of data, often termed a servo burst pattern, used to maintain optimum alignment of the read/write transducers over the centerline of a track when reading and writing data to specified data sectors on the track. The servo information may also include sector and track identification codes which are used to identify the location of the transducer.
Within the data storage system manufacturing industry, much attention is presently being focused on the use of an MR element as a read transducer. Although the MR head, typically incorporating an MR read element and a thin-film write element, would appear to provide a number of advantages over conventional thin-film heads and the like, it is known by those skilled in the art that the advantages offered by the MR head are not fully realizable due to the present inability of data storage systems to accommodate a number of undesirable MR head characteristics.
In particular, MR element transducers introduce a distortion in the sensed magnetic signal, which typically represents data or servo information stored on a magnetic storage disk. The distortion to the magnetic signal is caused by many factors, including a number of undesirable characteristics inherent in the MR element and the specific configuration and orientation of the MR element when incorporated into an MR transducer assembly. By way of example, it is known that a typical MR element exhibits variations in read sensitivity along the width of the MR element which has been identified as a contributing factor to servo control errors of varying severity. Depending on the magnitude of the magnetic signal distortion introduced by the MR element, servo sector information may, for example, be misinterpreted or unreadable, resulting in the possible interruption or loss of servo control or, in some cases, an irretrievable loss of the data stored on the disk.
A considerable amount of industry attention and resources have been, and continue to be, expended to develop solutions directed at reducing or eliminating the detrimental effects associated with a distorted magnetic readback signal. Such distortion in a readback signal obtained by an MR transducer has heretofore been treated collectively as undesirable noise without a full appreciation of the response of the MR element to varying influences encountered within its operating environment. As yet, no satisfactory solution has been found to eliminate or substantially reduce the magnetic signal distortion introduced by an MR element.
There exists a keenly felt need in the data storage system manufacturing community for an apparatus and method for eliminating the undesirable distortion to a magnetic readback signal induced in an MR element. There exists a further need to provide such apparatuses and methods which are suitable for incorporation into existing data storage systems, as well as into new system designs. The present invention is directed to these and other needs.